If an electro-static discharge (ESD) noise signal flows in an electronic system (4) at high speed, weak parts among the system parts are damaged. Thus, a technology for removing an ESD noise signal has been newly developed. An ESD noise signal has a great power (W/Dt). Herein, W is work in physics and Dt is time duration for work. As shown in FIG. 1A, W is great and Dt is small.
FIG. 1A shows a characteristic curve of noise signal in a graph of time relative to current (or voltage). A horizontal axis represents a time and a vertical axis represents a current (or voltage). In FIG. 1A, a voltage of ESD noise signal at time a is much higher than an ESD noise signal at time b or c. To effectively removing an ESD noise signal at time a is crucial.
FIG. 1B illustrates an ESD application system to which an MIT device is applied. Since an ESD noise signal generated in a power line (PL) supplying a power supply (2) can be removed by a MIT device (3) positioned between a node NO1 and a ground, internal parts of electronic system (4) can be protected from ESD.
A noise removing device for removing an ESD noise signal has to have a small standby current and has to have high reliability to effectively remove a high speed voltage ESD noise signal.